Exam 10: Inference About Means and Proportions With Two Populations

The following information was obtained from independent random samples taken of two populations. Assume normally distributed populations with equal variances. ​ The standard error of - is

The results of a recent poll on the preference of shoppers regarding two products are shown below. ​ The standard error of - is

The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card. You are given the following information. ​ A 95% confidence interval estimate for the difference between the average purchases of all customers using the two different credit cards is

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. ​ The p-value for the difference between the two population means is

A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information. ​ The standard error of - is

Salary information regarding male and female employees of a large company is shown below. ​ At 95% confidence, the margin of error is

A comparative study of organic and conventionally grown produce was checked for the presence of E. coli. Results are summarized below. Is there a significant difference in the proportion of E. coli in organic vs. conventionally grown produce? Test at α = .10.

When each data value in one sample is matched with a corresponding data value in another sample, the samples are known as _____ samples.

The standard error of - is the

The following information was obtained from matched samples taken from two populations. The daily production rates for a sample of workers before and after a training program are shown below. Assume the population of differences is normally distributed. ​ Given that the null hypothesis to be tested is H₀: μd = 0,

To construct an interval estimate for the difference between the means of two populations when the standard deviations of the two populations are unknown and it can be assumed the two populations have equal variances, we must use a t distribution with (let n₁ be the size of sample 1 and n₂ the size of sample 2) _____ degrees of freedom.

The results of a recent poll on the preference of teenagers regarding the types of music they listen to are shown below. ​ The 95% confidence interval for the difference between the two population proportions is

Salary information regarding male and female employees of a large company is shown below. ​ The 95% confidence interval for the difference between the means of the two populations is

In order to determine whether or not there is a significant difference between the mean hourly wages paid by two companies (of the same industry), the following data have been accumulated. ​ A point estimate for the difference between the two population means is

The sampling distribution of - is approximated by a

The following information was obtained from matched samples taken from two populations. The daily production rates for a sample of workers before and after a training program are shown below. Assume the population of differences is normally distributed. ​ The point estimate for the difference between the means of the two populations is

Salary information regarding male and female employees of a large company is shown below. ​ If you are interested in testing whether or not the population average salary of males is significantly greater than that of females at an α = .05, the test statistic is

Two major automobile manufacturers have produced compact cars with engines of the same size. We are interested in determining whether or not there is a significant difference in the mean MPG (miles per gallon) when testing for the fuel efficiency of these two brands of automobiles. A random sample of eight cars from each manufacturer is selected, and eight drivers are selected to drive each automobile for a specified distance. The following data (in miles per gallon) show the results of the test. Assume the population of differences is normally distributed. ​ The test statistic is

The management of a department store is interested in estimating the difference between the mean credit purchases of customers using the store's credit card versus those customers using a national major credit card. You are given the following information. ​ At 95% confidence, the margin of error is

An insurance company selected samples of clients under 18 years of age and over 18 and recorded the number of accidents they had in the previous year. The results are shown below. ​ We are interested in determining if the accident proportions differ between the two age groups. The p-value is